Fixes issue #673

[mattvaughan]

Most credit to @jewel for code. Mine differs only in the order of else's so that the minified version works.

[heff]

Thanks! I need to combine this with #1101, and then test it out.

[TrevorRawlings]

I'm loving videojs and full screen support for IE11 is an excellent addition but it looks like using msFullscreenElement results in a small difference in behaviour within vjs.Player.prototype.requestFullScreen().

Since msFullscreenElement returns a DOM element the vjs.on(document, 'MSFullscreenChange', ...) event listener doesn't get removed when exiting full screen.

I'm not familiar with the code so there's probably a more elegant solution but for me adding a !! worked around the problem:

if (!!this.isFullScreen() === false) {
vjs.off(document, requestFullScreen.eventName, arguments.callee);
}

[heff]

I built on top of this for #1205. If you can, check out the branch and see if it works for you.